How can I connect a Yamaha P155 Keyboard and an Apple G5 using Aux Out + Mic In?

I would like to connect a Yamaha P155 Keyboard to an Apple Macintosh G5 using the keyboards' AUX OUT L+R outputs and the Mac's MIC IN inputs. I have read on these forums that one needs to know if the AUX OUT outputs are balanced or unbalanced. This is not mentioned in the keyboard's documentation. I am not even sure the AUX OUT are line level since the master volume knob on the keyboard can be used to control the AUX OUT volume.

How can I tell if the outputs are balanced or unbalanced? Is this also an issue with the computer's MIC IN input? Does this mean that I need different cables for balanced than for unbalanced?

The aux outs on a keyboard are not likely balanced not that it would make a difference anyway for what your trying to do.

If your computer has aux in, that would be better than mic in but if not, you can still do it.(mic in will be more sensitive).

Just use two 1/4" to one stereo 1/8" pin jack cables.
Turn the volume on the keyboard down.
Set the volume in your computer at about half to start,then bring the volume on the keyboard up slowly and see how it sounds.

For starters, just hop on over to your local Radio Shack and look for a cable that has 2 mono 1/4" plugs on one end (for the AUX OUT on the keyboard) and a stereo 1/8" plug on the other (for the computer's mic in). If you can't find exactly that, you can construct one from (1) a stereo RCA patch cable, (2) a pair of RCA-to-1/4" adapters, and (3) an RCA-to-1/8"-stereo-plug adapter.

On most computers, the mic in can be configured for a line-level input (I've also seen it as disabling microphone boost). You'll want to choose that option.